SEOUL — North Korea has taken to the streets and to the propaganda sheets this week to celebrate its latest nuclear test, the huge explosion of what it says was a hydrogen bomb that can be attached to a missile.

With that test, and the recent demonstrations of great leaps in its missile technology, North Korea either now has a deliverable nuclear arsenal or is on the brink of having one. It is no longer a matter of if.

The few lingering questions about the country’s capability may be answered as soon as this weekend. South Korea’s intelligence service reported Tuesday that it had seen signs of preparations to launch another intercontinental ballistic missile that can theoretically reach well into the continental United States.

If history is anything to go by, the timing seems right. North Korea likes to stage provocations on significant dates, and on Saturday the regime celebrates its foundation as a state. On Sept. 9 last year, it marked the occasion with a nuclear test.

But amid the many questions about North Korea’s nuclear program, one is often overlooked: Why? Why is Kim Jong Un so hellbent on joining the nuclear club?

North Korea detonated their most powerful nuclear weapon yet in a test on Sunday, Sept. 3. President Trump responded to the test, calling the actions "hostile" and saying "we'll see" about a retaliatory attack on North Korea. (Monica Akhtar/The Washington Post)

The regime answered that question in its own way Tuesday when its state media reported how regular people and mid-level bureaucrats felt about the nuclear test.

“It is the best way to respond with powerful nuclear deterrent to the U.S. imperialists who are violent toward the weak and subservient to the strong,” Kim Chang Sok, a department director of the Ministry of Coal Industry, was quoted as saying, in words that sounded suspiciously like they came straight from the propaganda machine.

North Korea showed off a lot of missiles. What might be their targets?

“If you were the head of a small, isolated, poor country surrounded by potentially hostile military powers, you’d be looking for some way to ensure your own destiny, too,” said Jon Wolfsthal, a nuclear nonproliferation expert who served on President Barack Obama’s National Security Council.

North Korea has used its emerging weapons capability as a deterrent, betting that if it can threaten nuclear retaliation or even a conventional attack on South Korea, the United States will not take the risk of striking.

Contrary to an assertion by the U.S. ambassador to the United Nations, Nikki Haley, that North Korea is “begging for war,” all of the regime’s recent belligerence about destroying the United States has been couched as retaliation for an American preemptive strike, not as North Korea making the first move. That, Kim knows, would be suicidal.

But he looks at what happened to Saddam Hussein, the Iraqi leader who didn’t manage to develop nuclear weapons, and Moammar Gaddafi, the Libyan who gave up his nuclear program, and sees that he needs them to keep the United States at bay, analysts say.

“North Korea sees that in the 70 years that nuclear weapons have been in existence, no nuclear state has ever been invaded,” said Koh Yu-hwan, a professor of North Korean studies at Dongguk University in the South.

Now having the ability, or almost having the ability, to send a nuclear weapon to the United States makes those hyperbolic threats of devastating retaliation all the more credible.

“They know that they don’t have to destroy every American city to deter us,” Wolfsthal said. “They just have to make us think three times before attacking them.”

This helps explain why North Korea has been so much more bellicose than, for instance, Pakistan was when it was developing its nuclear arsenal: The United States is the intended audience and potential target.

But having a credible nuclear arsenal is not just about deterring the United States.

“The weapons are not the end. They are just the beginning,” said Daniel A. Pinkston, a Korea specialist who teaches at Troy University in Seoul.

While deterring the United States, North Korea will probably try to achieve its other objectives. Its stated goals include expelling the United States from the region, being recognized as a nuclear state and enjoying all the benefits and prestige that comes with that, and unifying the two Koreas on its terms.

This may sound like fantasy, but the North Korean regime believes it, Pinkston said.

“The Padres go to spring training every year thinking that they are going to win the World Series,” he said. “It’s the same with North Korea.”

There are also compelling domestic reasons that Kim would want nuclear weapons.

“This is a personal triumph for Kim Jong Un,” said Peter Ward, a researcher affiliated with the Asan Institute for Policy Studies in Seoul.

Not only has Kim’s regime made quantum leaps at an astonishingly fast pace, but it has done it amid sanctions that were supposed to stop it from getting the parts or the money it needed.

Now North Korea can say it is not reliant on anyone for its security and can credibly threaten to retaliate if it comes under attack — unlike Japan and South Korea, which depend on the United States for their defense.

“It’s a personal triumph for him with the North Korean elite, with the North Korean people. And there will be a lot of world leaders who will be very impressed,” Ward said. “Having a working nuclear deterrent turns the leadership from looking like a bunch of incompetent economic managers to being some of the most successful leaders on the continent.”

But some analysts wonder whether Kim’s urgency to become a fully fledged nuclear state belies some uncertainty about the 33-year-old’s position at the head of the regime.

“The fast pace of the nuclear and missile development may suggest that Kim Jong Un is confident, but it could also signal that he’s worried about the future,” said Kim Dong-yub, assistant professor at the Institute for Far Eastern Studies and a former South Korean navy commander who participated in military talks with North Korea.

“North Korea might think there is a low chance of an American attack for now, but there is no guarantee for the future,” Kim said.

So the question is no longer how to stop North Korea from getting nuclear weapons and the means to deliver them. It is how to persuade it to give up something it has spent so much time and money obtaining.

“There are three ways to resolve the North Korean problem,” said Lee Soo-hyuck, a former denuclearization negotiator who is now a South Korean lawmaker.

“North Korea giving up their nuclear weapons voluntarily, resolving through quid pro quo negotiations, and taking military action,” he said. “We all know the first and the last are not realistic options, so negotiation is the only way. We must not forget that.”

Can North Korea be persuaded to give up its nuclear weapons?

Not absent revolutionary change, Troy University’s Pinkston said. “It’s more likely that the pope is going to abandon Jesus Christ.”